Electronic devices, such as smartphones, tablet computers, and wearable devices, have become ubiquitous. The electronic devices often wirelessly communicate with remote servers and/or other devices over various types of connections, such as wireless local area networks (WLAN) (e.g., Wi-Fi, etc.), wireless wide area networks (WWAN) (e.g., LTE, CDMA, GSM, etc.), and personal area networks (PAN) (e.g., Bluetooth, ZigBee, etc.). Data may be transmitted and received by the electronic devices in order to facilitate their use. For example, users of electronic devices may be able to communicate using email, phone calls, Short Message Service (SMS), etc. by receiving and transmitting voice and data through a connection. The electronic devices may include antennas for communicating radio frequency (RF) signals without the need for a physical cable. RF signals are typically modulated to encode digital or analog information.
Portable electronic devices are often low profile and small. Moreover, users may desire a portable electronic device that is foldable to enjoy the benefits of a large display when the device is open and the reduced size when the device is closed, allowing them to wear the device on their arm and to store the device in their pocket, for example. The housing of a foldable electronic device may have, for example, two portions that are connected by a flexible hinge. The antennas may be integrated within one or both portions of the device at the bottom and/or the top ends. When the device is folded, the two portions of the housing may be generally adjacent to one another and a cavity may be formed between the hinge and the two portions of the housing. For example, the cavity may be open on three sides as magnetic boundaries, with the fourth side being the hinge and electrically shorted as an electrical boundary.
However, the cavity may absorb the RF energy radiated by the antennas, degrading the wireless communication capabilities of the device. In particular, a cavity may be formed when the device is folded, and the modes supported by the cavity may be within the spectrum of the RF frequencies of interest, causing degradations in the radiation efficiency. For example, the cavity mode may resonate at certain frequencies and absorb the energy radiated by the antennas. When this occurs at frequencies of interest, e.g., cellular radio frequencies such as 570 MHz to 960 MHz, 1450 MHz to 1660 MHz, 1710 MHz to 2200 MHz, 2496 MHz to 3800 MHz, and 4920 MHz to 5825 MHz, the antennas (and therefore the device) may not be able to wirelessly communicate in an optimal manner. Consequently, energy radiated by the antennas can be stored and dissipated within a cavity, which can prevent the signal from travelling away from the device to its intended destination, such as a cellular tower or other electronic devices.
Accordingly, there is an opportunity for foldable wireless electronic devices that address these concerns. More particular, there is an opportunity for the use of prescribed housing dimensions, ohmic contacts, and capacitive coupling that can attenuate the cavity modes created on foldable wireless electronic devices with minimal to small impact on the industrial design of the devices.